[Haskell-cafe] Re: Is my code too complicated?

Stephen Tetley wrote:

On 5 July 2010 11:30, Ertugrul Soeylemez wrote:

...

That's what monad transformers are good for.  Why reinvent the wheel?

The post was chiming in with Felipe Lessa's comment upthread that avoiding transfomers can have performance benefits.

Whether the formulation I gave is particulary efficient is moot - I'd have to give consideration to the strictness of the state at least - but I was answering Yves Parès about "how" you would do it, rather than "why".

Yes, there is some performance loss because of wrapping/unwrapping, but I think this loss is neglible for most applications. And I'd ask anyway. This is a discussion thread after all. =)

Given the status of MTL, I nowadays avoid transformers for pragmatic reasons rather than performance ones. If I have substantial code I'll rely on Iavor S. Diatchki's very nice MonadLib, but for small projects I'll just roll an amalgamated monad.

Almost all of my projects, including one published one, depend on monadLib. I find the MTL comparatively inconvenient. And especially for small projects I don't see why I should roll my own monad. I prefer to stick some transformers together. For larger applications my criterion is speed, but I've yet to see an application, where transformers are too slow. Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/